1. Field of the Invention
The present invention relates to a serial type recording apparatus. More particularly, the invention relates to an ink jet recording apparatus using for the ink jet head thereof an ink jet recording head that performs recording by discharging liquid, such as ink.
2. Related Background Art
For the recording apparatus, which is used as a printer, a recording unit for a copying machine or the like, it is generally practiced to adopt a serial type recording apparatus, that is, the one structured to record images on a recording medium in such a manner that while a sheet type recording medium, such as a recording paper sheet, or an OHP sheet, is being pinched for conveyance, the recording head, which is arranged on the carrying path of the recording medium, is allowed to scan. Of the recording apparatuses of the kind, the recording apparatus that uses the ink jet recording method makes running costs lower with a lesser amount of noises. Also, with such advantages that the apparatus can be downsized and arranged for color use with ease, it is used widely in general.
For the ink jet recording apparatus, the mechanism that conveys a recording medium while pinching it, the mechanism that records on the recording medium, the mechanism that expels the recording medium after the completion of recording, and the like are disclosed in the specifications of Japanese Patent Application Laid-Open No. 2001-246759 and others, for example. FIG. 9 and FIG. 10 are views that schematically illustrate the conventional example of such ink jet recording apparatus. FIG. 9 is a side view that schematically shows the entire body of the ink jet recording apparatus. FIG. 10 is a perspective view that shows the printer unit 520 that forms the principal part of this ink jet recording apparatus. Here, for convenience""s sake, the description will be made with the assumption that the side having a sheet-expeller tray 518 provided for the apparatus is in the front in the descriptions given below.
The printer unit 520 is formed by a plate member having a rear wall that expands almost at right angles to the bottom face of the bottom case 519, that is, the installation face of the recording apparatus, and side walls formed by folding the edge portions on both sides of this rear wall. It has the chassis 501 in the U-letter form as a whole (see FIG. 10). The chassis 501 is fixed to the bottom case 519 (see FIG. 9). Between the side walls of the chassis 501, there are supported the guide shaft 504 almost in parallel to the bottom face of the bottom case 519. With the guide shaft 504, and a guide portion arranged on the upper end of the chassis 501, a carriage 506 is supported to be able to reciprocate almost in parallel to the bottom face of the bottom case 519. For the carriage 506, a driving belt 510 is connected to enable the carriage 506 to reciprocate when the driving belt 510 moves circularly by means of a CR motor (not shown).
The carriage 506 has a recording head 508 mounted thereon in such a manner that the discharge port formation surface of the recording head is placed downward with the portion where the discharge port formation surface is provided is extruded downward. On the face of the carriage 506 on the rear side, there is provided a base plate 534 having the circuit that controls the operation of the recording head 508 arranged therefor. In front of the rear sidewall of the chassis 501, an encoder 507 is arranged in a stage of being biased. With this encoder 507 and a sensor (not shown) provided for the base plate on the carriage, the position of the carriage 506 is detected. The positional signal thus detected for the carriage 506 is utilized for the operational control of the carriage 506, and the recording head 508 as well.
On the backside of the chassis 501, an automatic sheet-feeding unit 517 is arranged on the bottom case 519. The automatic sheet-feeding unit 517 is provided so as to enable a pressure plate 426 and a sheet-feeding tray 527 to stand diagonally backward, on which plural sheets of recording medium 524 are stacked. The pressure plate 526 is fixed to the ASF base 525, which is installed on the bottom case 519 rotatively around the upper edge portion of the pressure plate 526, and the lower edge portion thereof is rotatively biased in the direction toward the front (in the clockwise direction in FIG. 9). Then, the sheet-feeding roller 528, which is axially and rotatively supported to the ASF base 525, is arranged in a position where the lower edge portion of the stacked recording medium 524 is pressed by the pressure plate 526 thus rotatively biased. A separation roller 529 is arranged in a position opposite to the sheet-feeding roller 528.
The sheet-feeding roller 528 is connected with a driving source (not shown), and it is driven to rotate for feeding a recording medium 524 when the recording operation begins. The pressure plate 526 is structured so that it is interlocked with the sheet-feeding roller 528 by means of a cam (not shown). Then, when a feeding is executed, it presses the recording medium 524 to the sheet-feeding roller 528, and on standby, it is pushed back against the biasing force given to it in the direction in which the lower edge portion thereof is placed backward. Therefore, on standby, the recording medium 524 can be stacked on the pressure plate 526 or removed freely. The recording medium thus stacked is held in a state where the lower edge thereof abuts against the rib, which is arranged for the ASF base 525.
At the time of sheet feeding, the separation roller 529 operates so that the recording medium 524 on the separation roller side is not allowed to be fed any further when plural sheets of recording medium 524 are inserted into a nip between the separation roller 529 and the sheet-feeding roller 528. Then, the recording medium 524 is separated and fed one by one from the automatic sheet-feeding unit 517.
In a location where the front edge of a recording medium 524 to be fed is bitten, there are arranged in the positions each other, the carrier roller 502 and the pinch roller 503, which are axially supported to rotate, respectively. The carrier roller 502 is axially supported by the bearings 512 formed on the sidewalls of the chassis 501, respectively. The pinch roller 503 is fixed to the pinch roller holder 513, which axially supports the pinch roller 503 on one end side, while being axially and rotatively supported between the sidewalls of the chassis 501 on the other end side. The pinch roller holder 513 is rotatively biased whereby to press the pinch roller 503 to the carrier roller 502.
The carrier roller 502 is connected with an LF motor (not shown), and the recording medium 524, which is pinched in the nip between the carrier roller 502 and the pinch roller 503, is conveyed by the rotation of the carrier roller 502. In this way, the recording medium 524 is conveyed in the sub-scanning direction intersecting with or orthogonal, in particular, to the main scanning direction in which the carriage 506 reciprocates.
Underneath the passage where the recording medium 524 is conveyed in such a manner, a platen 516 is arranged in a position opposite to the discharge port formation surface of the recording head 508 on the carriage 506 that reciprocates. The platen 516 is axially supported to rotate between the sidewalls of the chassis 501. In front of the platen 516, there are arranged the sheet-expeller roller 511 and the spur 514, which are axially supported to rotate, respectively. The spur 514 is biased by means of a spring toward the sheet-expeller roller 511. The sheet-expeller roller 511 is axially supported by a member that forms the platen 516, and then, connected with the LF motor through gears (not shown) so that it is interlocked with the carrier roller 502. The passage of the recording medium 524 being conveyed by the carrier roller 502 and the sheet-expeller roller 511 is arranged to extend almost in parallel to the bottom face of the bottom case 519.
Then, a sheet-expeller tray 518 is arranged in the position where the recording medium 524, which is pinched in the nip between the sheet-expeller roller 511 and the spur 514, is led out by the rotation of the sheet-expeller roller 511. The sheet-expeller tray 518 is arranged to extend diagonally forward and upward from the lower end of the bottom case 519 to the height of the sheet surface of the recording medium 524 to be conveyed on the platen 516.
In the traveling passage of the carriage 506, the right-hand end thereof is set at the home position, and then, suction recovery means 515 is provided for a portion below the location where the carriage 506 stays at this home position. The suction recovery means 515 is provided with a cap to cover the nozzles open to the discharge port formation surface of the recording head 508, and negative pressure generating means for making the inside of the cap negatively pressurized. The suction recovery means 515 sucks a certain amount of liquid from the nozzles, thus removing mixed dust particles and the ink the viscosity of which is made higher due to dryness. In this way, it functions to prevent the occurrence of such problem as to clog nozzles, which may be brought about by them otherwise. Also, this means is used for filling liquid in the nozzles in good condition. Also, for the suction recovery means 515, wiping means is provided for removing dust particles adhering to the discharge port formation surface by wiping them off from that surface.
The suction recovery means 515 and the automatic sheet-feeding unit 517 are arranged by positioning them in the predetermined positions with respect to the printer unit 520.
In accordance with the structure formed by use of the conventional art, which has been described above, most of the members that form all the mechanisms, such as the one used for recording, conveying a recording medium 524, and expelling the sheet, are incorporated in the printer unit 520. As a result, the chassis 501 of the printer unit 520 is given a heavy load due to the necessity of supporting the members needed for the provision of such mechanisms. If the strength and rigidity of the chassis 501 should be insufficient, it is conceivable that adverse effect is produced on the quality of recorded images due to the disturbance that may take place in the recording positions on a recording medium 524. Therefore, it is required for the chassis 501 to be sufficiently strong and rigid. This is one of the causes that increase the costs of the apparatus.
Now, with the improvement of the conventional art, the present invention is designed to aim at the provision of a recording apparatus of serial type, an ink jet recording apparatus, in particular, for which an inexpensive and simple structure can be used as the supporting member, while being capable of forming images in high quality without producing any adverse effect on the recorded images on a recording medium.
In order to achieve the aforesaid object, the recording apparatus of the present invention comprises a carrier roller rotatively and axially supported and driven to rotate for pinching and conveying a recording medium, and a pinch roller rotatively and axially supported to face the carrier roller; and a carriage supported above the recording medium to be conveyed, which is capable of reciprocating in the direction intersecting the conveying direction of the recording medium. The recording apparatus repeats the conveyance of the recording medium per designated amount, and the recording of images in the area of a designated width on the recording medium by the recording head mounted on the carriage, while enabling the carriage to reciprocate. The recording apparatus further comprises an assembled body having connected a base unit for axially supporting the carrier roller with a recording unit for supporting the carriage and the pinch roller, and the recording unit is provided with a chassis made in the form of a box as a whole by folding the upper and lower edge portions of a plate member, and also, by folding at least one of the ends thereof, and the carriage and the pinch roller are supported by the chassis.
With the structure thus arranged, the recording unit and the base unit dividedly support the carriage, the carrier roller, and the pinch roller. Therefore, as compared with the conventional example of supporting them with one member, the load, which is given to each of the supporting members of the recording unit and the base unit, can be reduced. Further, as the supporting member of the recording unit, a chassis made in the form of a box by folding the end portions of a plate material can be used, hence making it possible to obtain comparatively high strength and rigidity with a comparatively simple and inexpensive structure. Then, with the connection of a highly strong chassis with the base unit, it becomes possible to reinforce the base unit.
It is possible for the recording apparatus of the present invention to further comprise a sheet-feeding tray enabling the recording medium to be stacked thereon; and a sheet-feeding roller for feeding one of the recording medium stacked on the sheet-feeding tray one by one to a nip between the carrier roller and the pinch roller, in which one end of the sheet-feeding roller is axially supported by the recording unit, and the other end thereof is axially supported by the base unit. In this way, the recording unit and the base unit can share and bear the loads given by the sheet-feeding roller to them for the reduction thereof.
The carriage may be structured and slidably supported to reciprocate with the folded parts of the upper and lower edge portions of the chassis serving as a guiding portion therefor. With the structure thus arranged, it becomes possible to reduce the number of parts and attempt simplifying the apparatus, because there is no longer a need for the provision of a guide shaft required for the conventional art.
As described earlier, the connection with the chassis reinforces the base unit. Therefore, a comparatively low-strength material can be used for the supporting member thereof. Particularly, for the base that becomes the supporting member for the base unit, it is possible to adopt the inexpensive resin mold material that can be formed in various shapes with ease.
The recording unit and the base unit may be connected so as not to change the relative positions to each other, but may be connected through a connecting shaft so as to enable them to rotate relatively around the shaft. In either case, it is possible to obtain the reinforcement of the base unit with the connection with the chassis. Also, in the latter case, the recording unit and the base unit are enabled to rotate relatively around the connecting shaft to make it possible to locate them in a position having the carrier roller and the pinch roller arranged to face each other, and a position of the carrier roller and the pinch roller being apart from each other. With the structure thus arranged, it becomes possible to remove a jammed recording medium with ease by placing the carrier roller and the pinch roller to be in a state of being separated when paper jamming or the like occurs.
Also, for the recording apparatus of the present invention, it may be possible to arrange so that the chassis further supports a ring type driving belt connected with the carriage; plural pulleys having the driving belt being tensioned round them; biasing means for biasing at lest one of the pulleys in the direction to given tension to the driving belt; and a driving motor connected with one of the pulleys. With this structure, therefore, it is made possible to enable the carriage to reciprocate by driving the driving motor. Then, for the chassis, a belt stopper may be formed, which is provided with the wall face positioned with a designated gap to the outer circumferential surface of the pulley connected with the driving motor for at least a part of the portion having the driving belt tensioned. With the provision of such belt stopper, it becomes possible to prevent the driving belt from floating in the circumferential direction of the pulleys. It is advantageous to form this belt stopper so as to abut against a part of the carriage when the carriage moves beyond a designated area in the sliding direction thereof. In this manner, the carriage can be prevented from moving beyond the designated area.
As described above, the recording apparatus of the present invention is provided with the simple and inexpensive supporting members, but structured to be highly strong, hence making it possible to operate each unit in good precision for a precise recording operation. The characteristics of the kind are particularly desirable for an ink jet recording apparatus having an ink jet recording head mounted thereon to discharge liquid. The present invention is preferably applicable to the ink jet recording apparatus.